1. Field of the Invention
The present invention generally relates to a tape cartridge or a ribbon cartridge for use in printers such as tape printers and the like. In particular, the present invention pertains to a printer tape cartridge or a ribbon cartridge capable of avoiding degradation of ink ribbon placement workability, ease of ink ribbon transfer and other problems which may accompany printer downsizing.
2. Prior Art
In conventional printers, there are known printers which print a series of desired letters on a surface of a tape having on its back side an adhesive layer covered by a release paper, and thereafter cut the tape so that a label of a desired length can be obtained. In the present specification, this type of printer is referred to as a "tape printer". Printers of this type are used to readily obtain a label having desired letters, marks and the like printed thereon, and therefore it has been widely utilized domestically and in small-sized offices.
Such a tape printer is usually provided with a printing head of the thermal transfer type to facilitate downsizing of the printer. For the same reason, the tape printer is commonly provided with a transfer mechanism which transfers a tape or an ink ribbon in one direction passing through the printing head in a settled position to thereby carry out a printing operation.
The tape or ink ribbon provided for the tape printer is prepared in the form of a cartridge configuration capable of being releasably inserted into the main body of the printer, so that after the tape or ink ribbon runs out, the cartridge as a whole is replaced by a new one. In the present specification, a cartridge for a tape printer which holds both a tape and an ink ribbon therein is referred to as a "tape cartridge", so as to distinguish from an ink ribbon cartridge which holds only an ink ribbon therein and is utilized for commonly used printers.
The tape cartridge used for the conventional tape printer of the thermal transfer type has a main body case comprised by an upper casing part and a lower casing part in which a tape supplying section and a ribbon supplying section are accommodated. The tape and the ribbon dispensed from these sections are guided so that they are superposed at a position where a platen roll defining a printing position is placed. The tape, after being printed, is discharged outside from a tape exit formed in a case side wall, while the ink ribbon is wound at an ink ribbon recovery portion provided in the case. Paths for transferring the tape and the ink ribbon as mentioned above are defined mainly by inner surfaces of side walls of the case.
On the other hand, the tape printer is formed therein with a tape cartridge inserting section, into which the tape cartridge is releasably inserted. At the tape cartridge inserting section, there are provided a printing head mechanism, an ink ribbon winding drive shaft and the like. In an inserted condition of the tape cartridge, these portions are inserted into a printing head receiving portion and other portions formed in the tape cartridge side, so that the tape and the ink ribbon can be controllably transferred from the side of the tape printer, and at the same time the printing head is set in a position capable of printing on the tape at the position of the platen roll.
As mentioned before, there has been a demand for downsizing of tape printers, and for that purpose, downsizing of the tape cartridge inserting section and the tape cartridge itself is inevitably required. The tape and ink ribbon supplying sections cannot be reduced in size so long as the tape and the ink ribbon housed in the cartridge are maintained in length thereof. Thus, the tape path and the ink ribbon path must be configured so as to realize the downsizing of the cartridge. Specifically, since the ink ribbon path circulates through the inside of the case such that it extends from the ink ribbon supply section to the ink ribbon recovery section passing through the printing position, it is important to make this path as compact as possible. To this end, in the conventional tape cartridge, the width of the ink ribbon path in the case is set as narrow as possible.
However, the provision of the narrow ribbon path causes the following problems inevitably. First, the ink ribbon is placed in the tape cartridge such that the ink ribbon in the form of a roll is inserted into the cartridge case and is pulled out therefrom to reach the ink ribbon recovery section via the ink ribbon path. Thus, if the ink ribbon path is narrow, the operation of placing the ink ribbon through the narrow path is difficult to carry out.
Second, the ink ribbon may stick on the side walls or other surfaces of the case defining the narrow ink ribbon path. More specifically, the ink ribbon tends to become loose when the tape cartridge is inserted into or released from the inserting section of the tape printer, especially when the tape cartridge is inserted therein. The loose ink ribbon sometimes comes into a position in which it contacts the surface of the narrow path. If the ink ribbon is left in this position, the ink of the ribbon may stick to the surface of the path. This occurrence will adversely affect the ink ribbon transfer operation during the following printing cycle, thereby causing defects including degradation of print quality.
Conventionally, in order to prevent the tape from becoming loose, a ring-shaped leaf spring is placed between the end of the ribbon roll and the cartridge case so as to restrict the rotation of the ribbon roll to a certain extent. However, where friction between the leaf spring and the cartridge case is high, the ink ribbon cannot be rolled out steadily at a constant speed. On the other hand, the rotational shaft of the ink ribbon roll is supported, at both of its ends, rotationally on bearing parts formed in the upper and lower casing parts, respectively. In case the friction of the bearing parts is high, the stable transfer of the ink ribbon cannot be obtained. In consideration of these defects, lubricant oil is supplied between the leaf spring and the case, and between the both ends of the rotational shaft of the ribbon roll and the bearing parts of the case sides.
The lubricant oil supplied on these portions may be caused to flow toward the ink ribbon, causing the ink ribbon to become soiled. In particular, if the size of the tape cartridge is reduced, the gap between the lubricant-oil coated portions and the ink ribbon is small, and therefore there is a great danger that the ink ribbon is made dirty by the oil. In order to prevent the ink ribbon from being made dirty, the amount of lubricant oil supplied or coated must be strictly controlled.
On the other hand, the tape cartridge case is a molded piece made of an electrically nonconductive synthetic resin material. Thus, static electricity tends to build up in the tape cartridge during use. When the buildup of the static electricity exceeds a certain amount, arcing occurs between the tape cartridge side and the printing head mechanism of the tape printer, which becomes a noise source adversely affecting peripheral electronic equipment. If the tape printer is reduced in size, the respective portions of the tape cartridge are so located that they are close to portions of the tape printer side. This may increase the occurrence of arcing between the tape cartridge and the tape printer. However, conventional tape printers are not provided with a means for preventing the buildup of static electricity in the tape cartridge.